Sb elecric water pump design. School me on backing plates?

I may be overthinking this. In fact i must be since all mopar sb water pumps i have seen have backing plates.. BUT....is this not a recipe for cavitation?

The timing cover has a smooth recess for a WP impeller on a standard pump...

With an electric, you mount a smooth plate, but this does not block off the smoothed timing cover passage entierly. Even the moroso, which looks like it would bolt right to the timing cover, uses a backing plate...

Do electrics just blast SO much water that this gap doesnt matter? I cant help but picture this gap between the timing cover and backing plate holding air and all kinds if problems.

No doubt overthinking...just wondering how,why, and am i the only one to ever question this.