Nissan/Infiniti OEM VQ35DE 21010-AL528 Water Pump.
As the heart of the engine's coolant system. The water pump is what circulates the coolant through the engine, radiator and other passages. Over time the various seals can deteriorate and begin to leak coolant.
Its is suggested that a new water pump be installed whenever doing an engine build to ensure that all components in the coolant system are up to the task.