Well if anything, it will increase the rolling resistance.
Rolling resistance isnt the same as the friction you produce when you rub your hands together. If they were skidding down a mountain, then yes, water on the roads would make them go faster/further. But because the tyres flick up water constantly, energy is being lost moving the water around. Also, the tyres will be wet, so they will actually be slightly heavier.
Rolling resistance is more about how flexible the tyre is, and how well it can conform to the road in order to stop the momentum going in an upwards direction (eg: if you hit a stone, you want the tyre to conform, not to lift the whole bike up). Its also a little bit about how much the tyre sticks to the road, so how much energy is needed to lift the tyre away from the road. I dont know much about this, but logic would say that water might make a stronger bond between the road and tyre, acting almost as a glue. But I'm not certain.