Most of what I've read about hi-performance water pumps is that they are not necessary on a stock 4.0 and can even be harmful to the Jeep's cooling. The reasoning goes like this:
The water circulating through the engine moves heat around the engine and through the radiator, where it lets the outside air take some off. If the water doesn't spend enough time in the radiator, the air doesn't take enough heat off. The higher-flow water pump doesn't have any additional volume (larger hoses, bigger radiator, larger head passages, etc) to move water through, so to be "hi flow" it has to move the water faster. Less radiator dwell time, less cooling.
That, and I've heard stories about impellers blowing up & sending metal fragments through the cooling system, leaks, and other shenanigans.
Unless you are running a stroker or high compression motor with a larger radiator... I'd diagnose & repair the problem in your existing cooling system and / or replace your water pump with one from an OEM supplier.
