It's <u>possible</u> that the cam lobe is worn, but first I'd make sure you have the right pump. There is a long arm, and a short arm pump. The long arm requires a spacer between it and the block. If you install the short arm pump using the spacer, the actuating lever of the pump won't contact the cam.
Was the pump change to correct a "no run" problem?
Have you tried manually working the pump while off the car? There have been some shaky aftermarket pumps floating around lately.
Did you notice any metal in the oil the last time you changed it? For the cam lobe to wear to the point of uselessness, the oil should have looked like metallic paint.
In the event you switch to an electric pump, get one that puts out no more than 3 PSI.
Hope this has helped.
We'll get it figured out.
Jeff