The toggle switches would drive the relay coil and the relay would switch the actual power lines to the pumps. The coil on the automotive style relay is commonly considered to be between 50-200 ohms, so you're talking 0.3A worst case scenario and you'll need 2 per pump to handle reversing - so figure 0.6A per pump (could be as low as 0.12A). Those rocker switches are rated for much more (20A?)