Old water pump stuck in housing on 2004 Chevrolet Impala

I'm replacing my water pump. I've removed the pulley, and the mounting bolts, but I can't pull the water pump out of the housing. Is there something else I'm overlooking? thanks,

Asked by for the 2004 Chevrolet Impala
No big secret. Take a hammer and tap pump. Make sure you have all the bolts out.