Can electric power steering fail and what parts does electric power steering have?

Hi, thank you for answering my engine questions today about our 2014 Nissan Versa SV engine, I found out that our 2014 Nissan Versa SV is equipped with an electric power steering and thank heaven I won't have to worry about power steering hoses leaking power steering fluid but I am wondering can electric power steering fail and make the steering wheel very hard to turn and which parts does electric power steering consist of? I have heard that electric power steering has an electric motor on the steering wheel and a steering wheel position sensor? Is that it? Does it have a rack and pinion steering gear unit and tie rod ends? Can it fail and how much does it cost to replace a complete electric power steering unit on a 2014 Nissan Versa SV? Thank you in advance for your valuable information on electric power steering and for earlier information you supplied on our engine, our CVT transmission, and on our serpentine drive belt, your information is very useful and helpful to me