Do you read Polish? Polish language wiki has some info about these names.
It says that according to Polish etymologist
Aleksander Brueckner the element 'przem' means sincere, honest, forthright, etc.
http://pl.wikipedia.org/wiki/Przemys%C5%82aw_%28imi%C4%99%29
http://pl.wikipedia.org/wiki/Przezprzem