You've got a fancy pool pump there!
Vera and home automation in general do not have much analog capability. There are a few folks who chose to "roll their own" sensors etc but the majority of folks stay in the digital world.
Things you might consider:
- Depending on where your pool pump is (mine was in my back yard some distance from the house). Getting a reliable Z Wave signal to the pool might be an issue. That leaves keeping the Z wave module in the house and running the control signal to the pump. For this, the 4 - 20 ma signal excels. But you will find the conversion from Z Wave (perhaps PWM) to 4 - 20 ma a challenge.
- Before embarking on a direction with the pool pump, find how it handles transient commands. If the Vera control drops out and comes back quickly etc will it damage the pool pump?
Another though you might consider, Is it possible to limit the control authority of the Vera by pre-selecting 2 or 3 fixed settings. You can come very close to 4 - 20 ma control with a 24Vdc power supply (small wall wart) a few resistors and the Quibino RGBW.
Your instrumentation colleague should be able to help else I can be more specific if you wish.