To address the lubrication–wear failure problem of the aviation fuel piston pump (AFPP) slipper/swash plate interface operating under extreme conditions of high pressure ( 20 MPa ), high temperature ( 198 . 7 ° C ), high rotational speed ( 4000 r/min ), and low-viscosity medium ( 9 . 66 × 1 0 − 4 Pa⋅s ), where an ultra-thin oil film (0.83 μ m) is formed. This study comprehensively considers bidirectional fluid–structure–thermal interaction (FSTI), pressure and temperature induced elastic deformation, thermo-viscous effects, and asperity elasto-plastic contact, and, for the first time, incorporates adhesive/abrasive wear mechanisms and the transient dynamics of an inclined piston–slipper assembly into the hydrodynamic (HD) lubrication process. A transient mixed thermo-elastohydrodynamic lubrication wear-coupled model (MTEHD-W) is established. The accuracy of the model is validated by comparing leakage flow rate and energy loss predictions from the MTEHD-W model, the HD model, and analytical solutions under identical operating and structural parameters. The effects of different operating conditions and sealing band widths on leakage flow rate, energy loss, and lubrication–wear coupled characteristics are analyzed. The results indicate that the deformation, oil film thickness, pressure, and temperature distributions predicted by the MTEHD-W model agree well with literature data and experimental measurements. Compared with the HD model, the MTEHD-W model with bidirectional FSTI reveals that the thermal elastic deformation of the tin–bronze slipper (0.20 μ m) is greater than its pressure-induced elastic deformation (0.03 μ m), resulting in outer-edge wear in the high-pressure region and inner-edge wear in the low-pressure region. As the film thickness decreases, the inner-edge wear ( 15 . 2 × 1 0 − 6 μ m) exceeds the outer-edge wear ( 12 . 3 × 1 0 − 6 μ m). This asymmetric wear pattern is highly consistent with actual slipper wear morphology and the results of optimal contour design.