If you are running 1500w, 120v elements then you need a switch rated for 15a. For 2000w, 120v, you need a switch rated for 20a. Most of Auber's switches are not rated at that amperage, and are generally used to switch higher rated contactors. They do carry a 15a rocker switch.
Check the max amperage draw on your pumps to see what you need for them.
Also, I assume you will run each element off a separate 120v circuit, so there is no problem if both elements are firing. If that is not the case, you really need a 3-way switch (break before make) to ensure only one is firing at a time.