For an 8" x 10" water pump impeller, you have several material options:

1. Cast Iron: Known for its durability and resistance to wear, cast iron is a popular choice for pump impellers. It's suitable for handling water with moderate levels of solids or abrasives.

2. Stainless Steel: Stainless steel impellers offer excellent corrosion resistance, making them ideal for pumping corrosive fluids or water with high chloride content. They are commonly used in applications where hygiene and sanitation are important, such as food processing or marine environments.

3. Aluminium: Aluminium impellers are lightweight and offer decent corrosion resistance. They're often used in portable or mobile pump units where weight is a concern. However, they may not be as durable as cast iron or stainless steel impellers, particularly in harsh environments.

When selecting the material for your water pump impeller, consider factors such as the type of fluid being pumped, the operating conditions, and the required durability. Consulting with a pump manufacturer or supplier can help you choose the most suitable material for your specific application.