Wear and erosion wear represent primary failure mechanisms in flow passage components, and proactive preventive maintenance can effectively extend their service life. This study investigates the utilization of laser metal deposition technology for the additive manufacturing of 17-4PH stainless steel (17-4PHss) followed by solid solution aging treatment. Structural transformations before and after the solution aging treatment, along with the dry wear and erosion wear properties of 17-4PHss post-heat treatment, were examined. During the heat treatment process, the solid solution treatment fully transformed the microstructure to martensite, alleviating the stress generated by the additive process, and refined the microstructure to 0.64 μm. The subsequent aging treatment further refined the grains, ultimately reducing the grain size from 0.68 μm in the additive state to 0.62 μm. Compared to traditional casting, the grain size of 17-4PHss was reduced by 6.83%. Additionally, NbC was uniformly distributed in the sample, playing a secondary phase strengthening role, resulting in high microhardness (455.5 HV0.2). Simultaneously, the solid solution-aged (SSA) sample exhibited robust wear resistance, manifesting abrasive wear at low loads. With increasing load, a transition to abrasive wear and adhesive wear occurs, accompanied by oxidative wear and fatigue wear. At a 30 N load, the specific wear rate of the SSA sample decreased to 0.17 × 10−5 mm3/Nm, attributed to the more stable microstructure of the SSA sample under high loads. In the erosion wear test, the cumulative mass loss of the sample after heat treatment was the lowest (10.71 mg/m2h), with the erosion wear mechanism attributed to plastic deformation and micro-cutting.