I doubt this will be possible (and I'm a fan of wacky ideas)
Passing the PMA electricity through electromagnets (in the armature of a custom permanent magnet motor-PMM) on its way to do work somewhere else, is like hooking up a generator to two motors when its struggling to power one. You want 100% of your watts to go into the battery.
IF electromagnets (similar to a car alternator armature) could help the wheel move faster, the water would then become a restriction.
As a general rule of thumb, Water wheels can be calculated to run at about 90% of the water flow speed. This can give you a rough idea of the RPM's per a given diameter of wheel so you can plan out the rest of the system. As soon as the wheel rim began spinning 101% of the flow speed (again, if possible), it would not be getting any work from the water.
It begs the question, is it possible to design an electric motor connected to a generator, so that if I start it by hand-cranking it, will the motor spin the generator fast enough to power the motor, and possibly even have some extra power left over to use for work. Its been tried by people with electromechanical degrees and research money.
I'm a handy guy, and I could build a wheel pretty cheap. I think a well-matched PMA with neo magnets and copper wire will be much more expensive than the wheel. I think the device you're suggesting would cost near as much as a PMA, so for the cost of two PMA's and one wheel, I'd get (at best, if even technically possible) 10% more rim speed.
Financially its a better deal to build two wheels and two PMA's for guaranteed double the power.
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