The system does run at a relatively high pressure so a bad hose could be the issue. Clean off the hoses and the reservoir. Then have someone turn the wheels far left and right with the engine running while you look closely at the hoses and the reservoir. Also check the fluid level to see if it's where it should be under power and after sitting overnight. If you see no leaks and no new fluid along the hoses, it could be that the mess is from the mechanic who worked on the pump and didn't bother to clean up after.
Hopefully others will also chime in with more ideas.