The influence of duplex surface treatments consisting of a DC-pulsed plasma nitriding process and subsequent coatings of CrN and TiAlN deposited by physical vapor deposition (PVD) on AISI H13 tool steel was studied in this article. The treated samples were characterized using metallographic techniques, SEM, EDS, and microhardness methods. Hydro-abrasive erosion wear tests were performed in a specifically designed wear tester in which the samples were rotated in a wear tank containing a mixture of distilled water and ceramic abrasive chips with a fixed rotational speed. The wear rates caused by the abrasive particle impacts were assessed based on accumulated weight loss measurements. The worn surfaces were also characterized using optical microscopy, SEM, and EDS. Microhardness measurements indicated a significant increase in the surface hardness of the duplex-treated samples. The surfaces of the samples with the TiAlN coating were approximately 15 times harder than that of the untreated samples and 3 times that of the plasma nitrided samples. Hydro-abrasive erosion wear results showed that the duplex surface treatments, especially the CrN coating, displayed the highest erosion wear resistance.