An inner wall liner of a wall panel of a refrigerated trailer includes a liner sheet formed of fiber reinforced plastic (FRP) and a scuff plate formed of FRP. The scuff plate and the liner sheet are fused together such that the scuff plate is coupled to a bottom portion of the liner sheet. The inner liner further includes an upper wall plate formed of FRP. The upper wall plate and the liner sheet are fused together such that the upper wall plate is coupled to an upper portion of the liner sheet.