The Django book explains how Django was designed, and why each technical decision was made. It is not a cookbook. Surely, if you want to learn the fundamentals of web programming with a Python slant, you will struggle to do better. If nothing else, the discussion in the book will educate you about dark corners of web apps, like the need to escape everything, and why the model must be separated from the view, and how that can be achieved, what are the issues, how are SQL table joins managed from an ORM, and so.
In other words, I'm proposing that the Django book is, in a sense, an applied case-study in designing a web framework in python. Having said that, I recently read up a bit on web2py, and it sounds somewhat interesting. Their website has a lot of compare & contrast with other web frameworks (even non-Python ones), which should be of great interest to you in terms of learning how the standard problems of web programming have been tackled by various people.
I acknowledge the desire to understand all the details that "frameworks" hide, but it never pays to disregard the open literature, regardless of the field of study.