Depends on the pump. Can you post a picture?

Waterbug guy, here is a picture, I hope.

Couple of ways to go.

1. Get a replacement cord from the manufacturer.

2. You can get a 3 prong plug at the hardware store made to be a replacement like this.

3. Wire directly into a weatherproof box and switch which looks like:
{{gwi:235572}}

OK thanks for the advice, I got the weatherproof box and switch.