From a suitable motor factors get two colours of 10 amp wire, a 10 amp fuse holder and a switch rated to 10 amps. Run a feed back from your battery + terminal to where your pump is, wire in the 10 amp fuse and the switch. With the other colour wire pick up a good earth (perhaps from your rear lighting wiring), run both the positive and the earth to a double chocolate strip connector which you can then wire your pump to (this allows you to remove the pump without having to remove all of the wiring in the future).