Disclosed is a motor driven fluid pump (e.g., water pump) including a pump body having a motor chamber and a pump chamber; a bearing supporting a rotary shaft of a motor which extends from motor chamber to pump chamber in pump body; a mechanical seal disposed between rotary shaft of the motor and pump body and blocking motor chamber from pump chamber; a bearing guide integrally fixed to rotary shaft of the motor between bearing and mechanical seal; a fluidproof plate fixed to pump body to overlap bearing guide, perpendicular to rotary shaft of the motor; and a leachate exhaust aperture and a vapor exhaust aperture which are formed through pump body to communicate with the space between fluidproof plate and mechanical seal.