Obviously, as i stated this earlier that it's just 'my opinion'. But again, my opinion is based on certain experiences that I have come across. I have run a lot of 660s my self and that's where my opinion has come from.
Firstly, high wear and tear will only come if you use the car harshly. See, it's not made for power obviously but these engines would last a lot if you use them the correct way. See, if you put a lot of stress on the engine like if you race or use the car harshly then obviously the wear and tear would be more. That applies to all the engines not just 660's.
Secondly , i 660's have smaller engines but you should also consider the power to weight ratio. These cars are built smaller. The engine itself is smaller in weight. A 660cc car with 4 people sitting is not gonna put stress on the engine but if you accommodate 6 people then there will be a problem but again, its not gonna impact as much.
Thirdly not all parts are expensive. You can get a sealed engine of Mira 660 in just under 30k. Other daily usage parts are not expensive. But, yeah, in general these parts are more expensive than locally made ones but then again, all the imported cars have this issue. Not just 660cc cars.