One of the most important parts of your engine is the water pump.  Your Daewoo water pump functions by circulating coolant through the engines cylinder block, heads and radiator.  The coolant absorbs the heat that is put out from the engine blocks and dissipates it into the atmosphere through the radiator.  One of the most common reasons for water pump failure is leaking shaft seals.  The tell tale sign of a leaking shaft seal is a coolant stain around the vent area.  Noisy shaft bearings are the second most likely culprit of water pump failure.  Normal wear in the bearing or ordinary oxidation of the lubricant on the surface of the bearing will cause the bearing to fail.  The bearing can also fail if it is supporting an unbalanced fan assembly.  The third most typical reason water pumps break is the impeller slipping on the water pump shaft.  This occurs much more frequently on vehicles that have remanufactured water pumps.