Standard pumps won't work in space.
1. surface tension of water would stick to the lining of the pipes causing air bubbles in the middle of the pipe.
2. the lack of gravity will stop gasses from rising and liquids and solids from falling
2a Heat lingers in space, with no or micro gravity it doesn't rise above the dense air, so it would just linger in one place and sort of 'pool' causing the device to quickly burn itself out with it's own heat.
So, without the pump being safe for both gasses and liquid, without the pump being air cooled or liquid cooled, without the pump making it's own gravity...
The pump will work, but not for long, remember when you make a vacuum the water will boil and the hydrogen and oxygen will turn into a misty gas just like in well... a vacuum chamber.
Reference, Chris Hadfield, First Canadian Commander of International Space Station, builder of Space Station, Astronaut, Music lover.