Apart from the fact that Wundt is generally thought of as the "father" of modern psychological study, I know almost nothing about him.
James and Freud both worked on, and developed the concept of "self" - Freud refined "self" into id, ego and super ego.
That's probably the end of my knowledge (I nearly typed "understanding" there - which would have been an overstatement).
There is a lot of stuff out there on the web, it appears.