Let me try this.
Pole 1. control
pole 2. power
pole 3. control
that is how it should look on the back of the switch.
If you had a 6 pole you could jump the other side of the switch like that but with a 3 pole you can not. If you jump it at the switch like you state you will always have power.
The easy way is to run a wire from down by the pump where your control wires meet.
Also I would have a backup pump set at a higher level and you can hook up a buzzer (i use door bell) that lets you know you have high level water
I will look up a picture on how to wire it for you.