This document presents a mathematical model to optimize the aggregate production planning for a pump manufacturing company using a level strategy over a 12 month period. The objective is to minimize total costs by determining the optimal hiring, firing, production, inventory and shortage levels. A mixed integer linear programming model is formulated with decision variables for workforce levels, production, training, layoffs, firing, inventory and shortages. The model aims to maintain a stable workforce while meeting demand through inventory buffers. A case study and numerical problem from a pump company is used to demonstrate the model. The problem is solved using Python programming to arrive at optimal solutions for workforce allocation, production, inventory and shortages each month.