I'm not sure if the electric water pump is variable speed, or if it is just controlled with on/off cycles. My Davies Craig controller controls both the water pump and the radiator fan, and has alarms if there are problems or overheating, so you should be able to save the engine if there are issues.
A stock water pump is designed to flow enough water to keep the car from overheating when idling the engine on a hot summer day, with the AC on.
When the engine is revving near redline, there is way more water flowing than necessary, and power is wasted.
An electric water pump is also good for turbo cars, as it can cool down the turbo after the engine is turned off, rather than cooking the oil in the turbo.