Because I read that if the speed is not accurately synchronized, one of the motors will be applying more force, thus wearing faster.
well that is true. Unless you are using servo motors (to exactly know the position of the shaft) there is always a chance that one motor might move faster than other and cause trouble.
here's what you can do. If your movement is restricted ( not complete 360) attach a potentiometer to the shaft of each motor. Since the voltage output from the rotary pot will be propotional to the position of the shaft, you can always know (using ADC from your controller) which motor is going faster, and adjust the motor speed with PWM.
If the movement is not restricted (full 360 degree) use optical encoders for the same purpose listed above.
