NVDA doesn't have a command to read by word - purely because Windows already provides that functionality. Press CONTROL+LEFT ARROW to go back one word and CONTROL+RIGHT ARROW to go forward one word. Does Jaws have other commands for navigating through text like that? I can update our guide to switching from Jaws to NVDA to ensure that is covered. For what it's worth, these are all standard Windows commands:
LEFT / RIGHT ARROW - move back or forward by one character
UP / DOWN ARROW - move up or down by one line
HOME - move to the start of the current line
END - move to the end of the current line
CONTROL+LEFT ARROW / CONTROL+RIGHT ARROW - move back or forward by one word
CONTROL+UP ARROW / CONTROL+DOWN ARROW - Move up or down by paragraph (that doesn't work everywhere, and note that many programs treat any time you press ENTER as a paragraph).
PAGE UP / PAGE DOWN - move up or down by one screen worth of information
CONTROL+PAGE UP / CONTROL+PAGE DOWN move up or down by one page (in programs like Word which define a page)
CONTROL+HOME - move to the top or start of a document
CONTROL+END - move to the bottom or end of a document
The handy thing is you can hold SHIFT while pressing any of those and it will select text as well while it moves.