By inert, I mean one that doesn't have brass parts that contact the SW so as not leach metals into the tank (or chemicals etc.)
The coralife pump is a centrifugal pump, which means it has an impeller which can "chop" things up. Diaphragm pumps use a bellows like system to move water via positive displacement, which wouldn't grind up your pods etc. However there is a slight surging effect from single bellow pumps.
This is an example of an air-driven diaphragm pump:
Single
This is a double bellows and no surging
Double