The ECU is the main control system of a car and it controls any part of the car. Sensors ask for information, such as how much. Which sensor of the car? Every actuator is under the control of the ECU, so it is called the main component, and it is also called the Electronic Control Unit because it is electronically controlled.
Air Flow Meter
The main function of the Air Flow Meter is to measure the amount of air that enters the inlet, and the sensor is the Mass Air Flow Sensor (MAF).
Fuel pump
The fuel pump is a system used in diesel engines in the past. It used to be a mechanical governor sprinkler system. In cars with ECUs, a pump is now a mechatronic unit integrated with an electrical unit instead of a mechanical one. Also, the oil pressure pumped from the pump is generally 300 bars ~ 400 bars.