X-ray fluorescence analysis is used to determine wear of machine parts on a component-specific basis. The individual wetted wear surfaces of the machine are provided with a signature tagant composition, and as the components wear, the amounts of each tagant in the lubricating fluid are determined by the x-ray fluorescence analysis. An analysis system tracks the amounts of the tagants in the lubricating fluid, and with information of the signature tagant composition of each wear surface, calculates wear rate information for each of the wear surfaces. This component-specific wear information is then used in scheduling maintenance and predicting failures of the machine.