did you bleed the air out of the water system? if you dont do that all the new parts in the world wont help you. Find a cheap mechanic and have them bleed the cooling system. its not too hard but it can be messy. And check your thermostat. A new water pump should always include a thermostat replacement. Also, make sure your radiator cap is the right pressure and that the new radiator is the right radiator.
