Generally, you may not "change" to another nonimmigrant status after entering the US as a VWP visitor, so you will have to leave the US before you can work for this company.
See 8 CFR 248.2(a)(6):
(a) Except as described in paragraph (b) of this section, the following categories of aliens are not eligible to change their nonimmigrant status under section 248 of the Act, 8 U.S.C. 1258:
...
(6) Any alien admitted as a Visa Waiver Pilot Program visitor under the provisions of section 217 of the Act and part 217 of this chapter.
The exception in paragraph (b) concerns U visas, which are for victims of crime who are cooperating in the investigation of that crime.
Although this doesn't directly concern you, it's also not generally possible to "adjust" to lawful permanent resident status, but there is an exception for immediate relatives. See 8 CFR 245.1(b)(8):
(b) Restricted aliens. The following categories of aliens are ineligible to apply for adjustment of status to that of a lawful permanent resident alien under section 245 of the Act, unless the alien establishes eligibility under the provisions of section 245(i) of the Act and § 245.10, is not included in the categories of aliens prohibited from applying for adjustment of status listed in § 245.1(c), is eligible to receive an immigrant visa, and has an immigrant visa immediately available at the time of filing the application for adjustment of status:
...
(8) Any alien admitted as a Visa Waiver Pilot Program visitor under the provisions of section 217 of the Act and part 217 of this chapter other than an immediate relative as defined in section 201(b) of the Act;
