When the inlet pressure of a water pump falls below pump design specifications, tiny vapor bubbles can form in the water around the eye of the impeller. When the coolant containing these bubbles is forced into a high pressure environment on the other side of the impeller, these bubbles collapse, thereby creating tiny shock waves and points of high temperature. These shock waves may corrode the surface of the impeller and housing chamber.
Flowkooler pump impellers are designed for smooth pathway of contained coolant flow with vane shrouding and porting. It can't prevent it at the extreme rpm but it reduces the onset of cavitation for conventional driving.