a piece of work

There's nothing wrong with it, but it doesn't sound natural. An American would say "piece of work," usually ironically, to mean someone or something extraordinary. "Janet is making a fool of herself." "Yeah, she's a real piece of work."

In your example, i would expect an English-speaker to just say "essay."" More than one of the essays are well written.

If it's an essay as part of an academic course, you could also refer to it as an assignment.

Thank you all~

But for Setan, do you think your sentence is not the usual way?:

-More than one of the essays are well written.

My screen name is Setanta, not "Setan." More than one is plural. The third person plural of to be is "are."

Thank you~

So you would always say 'More than one person were injured' and never 'More than one person was injured'?

Yes.

Not me.

Thank you~