<TabControl TabStripPlacement="Left">
...
</TabControl>
Then you put the icons in the Header property of the TabItems and the UserControls in the Content property. That will get you about halfway there. If you want the exact same look you'll need to retemplate the TabControl and TabItem by copying the current template (use Blend or ShowMeTheTemplate to copy the current template) and modifying it as needed. But just changing those properties will let you test whether a TabControl gets rid of your focus issues.
Edit: Here's an example template that should be pretty close to your screenshot
<Style TargetType="{x:Type TabItem}">
<Setter Property="Background" Value="Transparent" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TabItem}">
<Border x:Name="PART_Border" Background="{TemplateBinding Background}" BorderThickness="1" BorderBrush="LightGray" Margin="2">
<ContentPresenter ContentSource="Header" Margin="2" />
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter TargetName="PART_Border" Property="BorderBrush" Value="Black" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style TargetType="{x:Type TabControl}">
<Setter Property="TabStripPlacement" Value="Left" />
<Setter Property="Margin" Value="2" />
<Setter Property="Padding" Value="2" />
<Setter Property="Background" Value="White" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TabControl}">
<Grid ClipToBounds="True" SnapsToDevicePixels="True" KeyboardNavigation.TabNavigation="Local">
<Grid.ColumnDefinitions>
<ColumnDefinition Name="ColumnDefinition0" />
<ColumnDefinition Width="0" Name="ColumnDefinition1" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" Name="RowDefinition0" />
<RowDefinition Height="*" Name="RowDefinition1" />
</Grid.RowDefinitions>
<Border x:Name="HeaderBorder"
BorderBrush="Black"
BorderThickness="1"
CornerRadius="5"
Background="#FAFAFA"
Margin="0,0,0,5">
<TabPanel IsItemsHost="True"
Name="HeaderPanel"
Panel.ZIndex="1"
KeyboardNavigation.TabIndex="1"
Grid.Column="0"
Grid.Row="0"
/>
</Border>
<Grid Name="ContentPanel"
KeyboardNavigation.TabIndex="2"
KeyboardNavigation.TabNavigation="Local"
KeyboardNavigation.DirectionalNavigation="Contained"
Grid.Column="0"
Grid.Row="1">
<Border Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
CornerRadius="5">
<ContentPresenter Content="{TemplateBinding SelectedContent}"
ContentTemplate="{TemplateBinding SelectedContentTemplate}"
ContentStringFormat="{TemplateBinding SelectedContentStringFormat}"
ContentSource="SelectedContent"
Name="PART_SelectedContentHost"
Margin="2"
SnapsToDevicePixels="{TemplateBinding UIElement.SnapsToDevicePixels}"
/>
</Border>
</Grid>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="TabControl.TabStripPlacement" Value="Bottom">
<Setter TargetName="HeaderPanel" Property="Grid.Row" Value="1" />
<Setter TargetName="ContentPanel" Property="Grid.Row" Value="0" />
<Setter TargetName="RowDefinition0" Property="RowDefinition.Height" Value="*" />
<Setter TargetName="RowDefinition1" Property="RowDefinition.Height" Value="Auto" />
<Setter TargetName="HeaderBorder" Property="FrameworkElement.Margin" Value="0,5,0,0" />
</Trigger>
<Trigger Property="TabControl.TabStripPlacement" Value="Left">
<Setter TargetName="HeaderPanel" Property="Grid.Row" Value="0" />
<Setter TargetName="ContentPanel" Property="Grid.Row" Value="0" />
<Setter TargetName="HeaderPanel" Property="Grid.Column" Value="0" />
<Setter TargetName="ContentPanel" Property="Grid.Column" Value="1" />
<Setter TargetName="ColumnDefinition0" Property="ColumnDefinition.Width" Value="Auto" />
<Setter TargetName="ColumnDefinition1" Property="ColumnDefinition.Width" Value="*" />
<Setter TargetName="RowDefinition0" Property="RowDefinition.Height" Value="*" />
<Setter TargetName="RowDefinition1" Property="RowDefinition.Height" Value="0" />
<Setter TargetName="HeaderBorder" Property="FrameworkElement.Margin" Value="0,0,5,0" />
</Trigger>
<Trigger Property="TabControl.TabStripPlacement" Value="Right">
<Setter TargetName="HeaderPanel" Property="Grid.Row" Value="0" />
<Setter TargetName="ContentPanel" Property="Grid.Row" Value="0" />
<Setter TargetName="HeaderPanel" Property="Grid.Column" Value="1" />
<Setter TargetName="ContentPanel" Property="Grid.Column" Value="0" />
<Setter TargetName="ColumnDefinition0" Property="ColumnDefinition.Width" Value="*" />
<Setter TargetName="ColumnDefinition1" Property="ColumnDefinition.Width" Value="Auto" />
<Setter TargetName="RowDefinition0" Property="RowDefinition.Height" Value="*" />
<Setter TargetName="RowDefinition1" Property="RowDefinition.Height" Value="0" />
<Setter TargetName="HeaderBorder" Property="FrameworkElement.Margin" Value="5,0,0,0" />
</Trigger>
<Trigger Property="UIElement.IsEnabled" Value="False">
<Setter Property="TextElement.Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
It's basically a copy of the normal TabControl with some Borders added and removed. Hope that helps.