Currently there are two ways to integrate WeBWorK with Moodle. Each has its own advantages and disadvantages.
Moodle Assignment provides a loose coupling between WeBWorK and Moodle which allows a student in a Moodle course to enter the corresponding WeBWorK course without reauthorization. In addition the grades from the WeBWorK course are automatically entered into the Moodle gradebook.
The Moodle Question Type embeds WeBWorK functionality into a mathematics question type that can be used in Moodle quizzes. WeBWorK's ability to analyze answers to mathematics questions and all of the questions in the WeBWorK question bank become available for use within Moodle. Users more comfortable with Moodle and the Moodle Quiz module will probably prefer the Question Type.